The wind has historically been one of the most widely used natural resources to provide the energy necessary to power our needs. As the demand for energy has increased and the supplies of fossil dwindled, resulting there has been a renewed look by electrical utility companies at alternative methods for producing electrical power. One method of electrical production involves the harnessing of the wind by a wind turbine to drive an electrical generator.
Wind turbines typically involve using a series of blades fixed to the top of a tower to rotate about a horizontal axis. The blades have an aerodynamic shape such that when a wind blows across the surface of the blade, a lift force is generated causing the series of blade to rotate a shaft about an axis. The shaft is connected, typically via a gearing arrangement, to an electrical generator located in a structure called a nacelle which is positioned behind the blades.—[No gearbox on this design]
The nacelle houses a number of components which are needed in modern high capacity wind turbines. In addition to the aforementioned generator, other components include a yaw drive which rotates the wind turbine, various controllers, and a brake that is used to slow the generator. Since it is desirable to keep the nacelle as small as possible, and given the number of relatively large pieces of equipment which must be located in the nacelle, space becomes very valuable. This often results in difficulties in both manufacturing the wind turbine and in conducting maintenance operations in the nacelle once the wind turbine is installed.
Typically, the nacelle will also incorporate a system for cooling components, especially the electrical generator. These cooling systems usually utilize some type of active cooling, such as cooling water or fans. Alternatively, some wind turbines have directed cooling air for circulation within the generator housing and nacelle. Each of these methods of cooling result has resulted in disadvantages, i.e. a lower efficiency or acoustical issues.
Accordingly, it is considered desirable to provide a wind turbine which provides a passive means for cooling the wind turbine generator.